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Corrugated cement asbestos roofingCorrugated Asbestos Cement Roof Materials

  • CORRUGATED CEMENT ASBESTOS ROOFING - CONTENTS: Corrugated Cement-Asbestos Roofing Guide. Properties, age, asbestos content, maintenance & repair of corrugated cement roofing. Typical Life of Cement Asbestos Roofing. Cement asbestos roof stains. Cement asbestos roof demolition. Sources of Replacements for Corrugated Asbestos Cement Roofing
  • POST a QUESTION or READ FAQs about identifying & maintaining or removing asbestos cement corrugated roofing
  • REFERENCES
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Guide to asbestos cement corrugated roofing:

This article provides a photo guide and text that can identify the condition of cement asbestos roofing products like asbestos-cement roof shingles.

We discuss how to identify corrugated cement asbestos roofing and how to treat this material when found on a building.



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Corrugated Cement-Asbestos Roofing Guide

Corrugated cement asbestos roofing

Asbestos cement roof shingles were in popular use in the U.S. from the 1920's (est) through the 1960's (est) and were sold in the U.S. into the 1970's and according to some sources even in the 1980's.

The mixture of asbestos fibers and portland cement to form a hard material that was was durable and fire resistant is credited to Ludwig Hatschek who, in 1900, came up with the name Eternit associated with a U.S. producer of these products.

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Article Contents

Large Asbestos-Cement Sheet Goods Production

Amy Lamb Woods, in "Keeping a Lid On It" Asbestos-Cement Building Materials" provides a superb and concise description of the history and properties of asbestos cement building products, while beginning at ASBESTOS ORIGIN & NATURE we provide the compete text of Rosato's 1959 seminal work on this topic. The following excerpts are from Woods (2000):

Large flat asbestos - cement sheets were available in sizes of twelve - feet long by four - feet wide and thicknesses ranging from approximately an eighth of an inch to one inch. Asbestos-cement flat sheets were, at one time, manufactured only in the typical gray color of cement and usually only accepted for industrial purposes. Eventually sheets were made with smooth surfaces, waxed or lacquered, with a variety of colors for use as office partition walls, kitchen walls, tabletops, acoustical panels, and building corridors. They were often used where ease of cleaning was important. One popular material for interior lining was an embossed sheet with a figured pattern that could be painted or distempered, thus providing the effect of plaster at a relatively low cost.

Another popular variation consisted of a smooth surface and wood - grain appearance available in a range of colors. Some sheets were glazed, thus presenting a smoother, more resilient finish. Flat sheets were often incorporated into composite products. ‘Transitop’ was a typical composition board consisting of an integrally impregnated insulating board core, faced on both sides with asbestos-cement board. Waterproof adhesives were used to laminate the insulating core as well as to bond the noncombustible asbestos - cement faces to the core. ...

The Hatschek machine made possible the production of large asbestos-cement sheet goods. See CEMENT ASBESTOS PRODUCT MANUFACTURE for details of the Hatschek machine and its operation.

With the advent of asbestos-cement corrugated sheets, the enclosure of factory buildings, warehouses, and train sheds was simple, economical, an d effective for either permanent or portable structures. Corrugated asbestos - cement sheets were applied in the same way that corrugated iron was applied, either nailed to wooden strips, bolted to the purlins, or clipped directly to the purlins by clips of hoop - iron or wire.

They were available in standard sheets, twenty - seven and a half inches wide and in lengths of four, five, six, seven, eight, and ten feet.

Two primary shapes were Trafford (with peaks), and Fibrotile (with waves). A series of special hardware devices was designed for use with corrugated sheets so that buildings could be completely encased in the material. Corrugated asbestos - cement sheeting was also used for decorative purposes in uniquely styled buildings of all descriptions.

During t he 1940s construction boom, a wider variety of colors became available, including a spackled look, where the colors were impregnated throughout the sheet so they would not powder or peel off. When color change became desirable after installation, owners we re encouraged to paint the asbestos-cement products. It was the “attractive home safeguarded with modern asbestos siding, fireproof, rot proof, termite proof” idea that intrigued many Americans during this era. By 1950, approximately one billion square feet of asbestos-cement products had been produced for use in the building industry. - Woods (2000)

Typical Life of Cement Asbestos Roofing

The typical life expectancy of an cement asbestos shingle roof was given as 30 years, But we have seen these roofs that were now 50 years old in good condition. Typical roof wear or failure patterns are either failure of the shingle fasteners or broken and falling shingles.

Virtually all of the asbestos cement roof shingle inspection points, installation limitations, and environmental concerns which we discussed at Guide to Cement-asbestos roof shingles also apply to corrugated asbestos-cement roofing products.

OPINION: The lichens growing on cement-asbestos roofing (photo at left), especially this thick corrugated material, is probably less of a wear concern than when that material appears on asphalt shingles or roll roofing.

Do not try to walk on this material without taking the same precautions as if accessing a slate roof: the material is easily damaged by foot traffic.

Cleaning stains, mold algae, lichens from cement-asbestos roofs

Watch out: As we discuss at POWER WASHING ROOFS we do not recommend power-washing asbestos-cement nor any other roofing.

However there are techniques for preventing or killing off algae growth that stains roof surfaces.

See BLACK ROOF STAIN REMOVAL & PREVENTION for advice on diagnosing, cleaning, and preventing stains on roofing.

Maintain or Remove Corrugated Asbestos or Fiber Cement Roofing?

Reader Question: What should I do about corrugated fiber cement roofing on my home - is it asbestos? Is it dangerous?

Corrugated cement roofing (C) D Friedman S.S.

I just bought my house. It was inspected a friend who saw my roof, photos [above and below] and who says it is asbestos. Can you tell by looking at a photograph if this is an asbestos-cement roof ?

Corrugated cement roofing (C) D Friedman S.S.

Reply: It depends ...

Corrugated cement roofing (C) D Friedman S.S.

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem or that can more accurately estimate the age and thus the chances that your corrugated roof is an asbestos-containing product.

That said, here are some things to consider:

Those questions can also help answer your question about asbestos roofing.

What to do with this corrugated fiber cement or asbestos cement roof

Planning demolition of corrugated cement asbestos roofing materials?

Corrugated asbestos cement or fiber cement used in the interior of a building (C) InspectApedia.com GS

The risk of high levels of airborne asbestos from cementious roofing products is probably very low unless the workers are using power equipment like sanders and saws on these substances.

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According to NRCA, the National Roofing Contractors' Association, their studies up to February 1992 had not found a single roofing job at which these limits were exceeded, and NRCA reported that in some cases no fiber release was detected.

But it appears that the association may have been referring only to asphalt-based roofing materials, not jobs involving the demolition of other ACRM such as cement-asbestos roof shingles (or "asbestos roof tiles" as some consumers refer to them) which might produce different statistics.

See ASBESTOS MATERIAL REGULATIONS

and ASBESTOS REGULATION Update that address the handling of asbestos containing building materials, including ACM (asbestos containing materials), PACM (presumed asbestos containing materials), SACM (suspect asbestos containing materials), and ACRM (asbestos containing roofing materials).

Reader Question: what are the engineering properties of transite roof decking (cement asbestos roofing)?

I need to find the engineering properties of a specific profile of transite roof deck. Please see the attached sketch and picture. I will gladly purchase the correct catalog if you can help me identify which catalog that is. - Anon, 11/18/2014

Asbestos cement roof condition analysis (C) InspectApedia GS

Reply:

For engineering properties of a contemporary material you'd find easiest results contacting the manufacturer. And Woods (2000) cites Hannant (1978) as a source for the engineering properties of various fiber cement roofing materials.

The original properties of corrugated cement roofing using asbestos, which you referred to as transite roofing, can also be found in some early patent applications, though I have not seen complete engineering analysis of the materials strengths and other properties in those documents.

For the engineering properties of an older asbestos-cement roofing product (which is what I think I see in your first photo above and again at left) that is of course no longer in production one might find an old specification document but in my OPINION that would be dangerously misleading as weathered, worn building materials change in properties such as density and impact resistance.

My experience with direct inspection as well as owner reports of older fiber cement and asbestos cement and corrugated asbestos cement is that the material becomes quite fragile - at that age its properties would be quite different from the original product specifications.

For that situation, if it were actually justified, one would have to send representative samples of the material to a materials testing laboratory - which of course raises its own issues about roof damage and material disturbance.

Reader Follow-Up

Single ply roof over corrugated asbestos cement roof decking (C) InspectApedia GS

I notice in one of the links you provided that the life expectancy of cement asbestos shingles was given as 30 years with some 50 years old roofs in good condition.

Flat roof over corrugated asbestos cement roofing (C) InspectApedia GS

Reply:

The most detailed analysis of the engineering properties of Asbestos-Cement roof decking materials is the by el Hakim cited below. His conclusion begin on p. 280 of the thesis and are illuminating.

But again I emphasize that as with other building materials, after years of service the mechanical properties of asbestos cement are likely to be different than when first produced, more-so if exposed to the weather or to leaks and/or freeze-thaw cycles or to the effects of algae or cyanobacteria and of course if exposed to mechanical damage or stresses.

My own direct inspection as well as field anecdotal data show that the when exposed to the weather, more water and temperature variations than sunlight, asbestos cement products used on roofs tend to become soft and quite fragile. Effects of biological agents, particularly lichens, moss and to a degree, fungi also play a role in this deterioration.

Common Forms of Cement Asbestos Roof Wear & Deterioration

My opinion (I am not an engineer but have field experience and have done some research on the topic) is that if the corrugated asbestos-cement roof decks you describe have been protected from the weather (including leaks through the roof membrane) and thus from water and freeze-thaw cycle effects then the materials may be in better condition than the roofs I've inspected that have been directly exposed to the weather. Asbestos cement roof deterioration elements we expect to find in the field include:

Importance of Visual Assessment of Asbestos-Cement Roof Condition

However without lab testing combined with an intelligent assessment of the extent of roof area over which a particular form of deterioration is observed, in my opinion, a quantitative statement of roof life remaining would be unreliable. See Giller (1993) on visual assessment of roof decking.

A more detailed inspection of the asbestos-cement corrugated material-roofed building(s) you are evaluating is needed to determine the leak history as well as to find other instances of mechanical or other damage to the roofs. Certainly one of your photos shows one of the worst, most heaved, out of flat membrane roof surfaces I have seen. One might choose the most-suspect roof area for further, more invasive inspection or materials testing.

In my opinion, an astute roofer would be reluctant to accept a roof-over job on such a roof because of lack of confidence in the durability of that approach, or s/he would make clear in writing that there was little or now warranty on the roof job unless the new roof could be installed over an appropriately secure and smooth roof deck.

Also you may want to take a look at ASTM E2394 and at Oberta's proposed Standard for repair and maintenance of Asbestos-Cement materials.

Fiber cement roof life expectancy research & maintenance standards of interest:

References for the Properties of Corrugated Cement Roofing & Siding Products

In addition to the citations at REFERENCES

Other Research Citations on Asbestos Cement Roofing

Sources of Replacements for Corrugated Asbestos Cement Roofing

Corrugated fiber cement roofing (C) Daniel Friedman

Contemporary roofing product manufacturers make reinforced fiber-cement roofing shingles and other roofing products which look like, perform similarly to, and need to be installed similarly to the original corrugated asbestos-cement sheet roofing - but these new products are free of asbestos. (Photo at left: author points to new fiber cement roofing product.)

As we explained in our discussion of cement asbestos shingles, the replacements for corrugated asbestos cement roofing products are reinforced with a variety of fibers including fiberglass.

Other replacements for asbestos-cement roofing use both different fibers and a different aggregate (perlite) to replace the asbestos. Some of the substitute products have been in use for more than 30 years (2008).

Sources of modern fiber cement corrugated roofing (non-asbestos):

For handling and disposal guidance concerning old roofing material contact the US EPA, your state Department of Environmental Protection/Conservation, or your local building and health departments.

Asbestos-Cement Roofing Articles

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